Viruses are highly efficient at nucleic acid delivery to specific cell types, while often avoiding detection by the infected host immune system. These features make certain viruses attractive candidates as gene-delivery vehicles for use in gene therapies. Retroviral vectors are the most commonly used gene delivery vehicles. The retroviral genome becomes integrated into lost chromosomal DNA, ensuring its long-term persistence and stable transmission to all future progeny of the transduced cell and making retroviral vector suitable for permanent genetic modification. Up to 8 kilo bases of foreign gene sequence can be packaged in a retroviral vector particles, which is more than enough for most gene therapy applications. The ability of retroviral vector particles to cause no detectable harm while entering their target cells represents another therapeutically important property. Retroviral based vectors can be manufactured in large quantities, which allows their standardization and use in pharmaceutical preparations. Most of the commonly used retroviral vectors are of uncovered origin. These vectors require cell division in order to achieve genome integration and long-term gene expression.
Lentiviral vectors are a particular type of retrovirus vectors. They have also been used as agents for the direct delivery and sustained expression of a transgene. Lentiviral based vectors can efficiently transduce dividing and non-dividing cells in these tissues, and maintain long-term expression of the gene of interest.
There is a need in the art for means for more efficiently transfecting retroviral vectors or transducing recombinant retroviruses in gene transfer. The present invention addresses this and other needs.